L2VPN Multisegment Pseudowires

First Published: February 27, 2009

Last Updated: November 20, 2010

The L2VPN Multisegment Pseudowires feature enables you to configure two or more Layer 2 pseudowire segments that function as a single pseudowire. Layer 2 Virtual Private Network (L2VPN) multisegment pseudowires span multiple cores or autonomous systems of the same or different carrier networks. L2VPN multisegment pseudowires are also used in L2VPN Virtual Private LAN Services (VPLS) Inter-AS Option B networks.

This document explains Multiprotocol Label Switching (MPLS) Operations, Administration, and Maintenance (OAM) Support for L2VPN Multisegment Pseudowires and the MPLS OAM Support for the L2VPN VPLS Inter-AS Option B feature. These features allow you to use ping mpls and trace mpls commands to ensure pseudowire connectivity.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the "Feature Information for L2VPN Multisegment Pseudowires" section.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn.An account on Cisco.com is not required.

Information About L2VPN Multisegment Pseudowires

L2VPN Pseudowire Defined

An L2VPN pseudowire (PW) is a tunnel established between two provider edge (PE) routers across the core carrying the Layer 2 payload encapsulated as MPLS data, as shown in Figure 1. This helps carriers migrate from traditional Layer 2 networks such as Frame Relay and ATM to an MPLS core. The PWs between two PE routers are located within the same autonomous system (AS). Routers PE1 and PE2 are called terminating PE routers (T-PEs). Attachment circuits are bounded to the PW on these PE routers.

Figure 1 An L2VPN Pseudowire

L2VPN Multisegment Pseudowire Defined

An L2VPN multisegment pseudowire (MS-PW) is a set of two or more PW segments that function as a single PW, as shown in Figure 2. It is also known as switched PW. MS-PWs span multiple cores or autonomous systems of the same or different carrier networks. An L2VPN MS-PW can include up to 254 PW segments.

Figure 2 A Multisegment Pseudowire

The end routers are called terminating PE routers (T-PEs), and the switching routers are called S-PE routers. The S-PE router terminates the tunnels of the preceding and succeeding PW segments in an MS-PW. The S-PE router can switch the control and data planes of the preceding and succeeding PW segments of the MS-PW. An MS-PW is declared to be up when all the single-segment PWs are up. For more information, see the L2VPN Pseudowire Switching document.

With the L2VPN Multisegment Pseudowire feature introduced in Cisco IOS Release 12.2(33)SRE, the pseudowires are created statically, and FEC 128 information is used to exchange the information about each AS.

MPLS OAM Support for Multisegment Pseudowires

You can use the pingmpls and trace mpls commands to verify that all the segments of the MPLS multisegment pseudowire are operating.

You can use the ping mpls command to verify connectivity at the following pseudowire points:

•From one end of the pseudowire to the other

•From one of the pseudowires to a specific segment

•The segment between two adjacent S-PE routers

You can use the trace mpls command to verify connectivity at the following pseudowire points:

•From one end of the pseudowire to the other

•From one of the pseudowires to a specific segment

•The segment between two adjacent S-PE routers

•A range of segments

MPLS OAM Support for L2VPN VPLS Inter-AS Option B

The L2VPN VPLS Inter-AS Option B feature introduced in Cisco IOS Release 15.1(1)S uses multisegment pseudowires to connect Autonomous System Border Routers (ASBRs) in different autonomous systems. With this feature, the pseudowires are created dynamically, and FEC 129 information is used to exchange the information about each ASBR.

The differences between static multisegment pseudowires and dynamic multisegment pseudowires are listed in Table 1.

Provides a description of the switching provider edge router for a multisegment pseudowire.

Step 11

neighborip-address vcid {encapsulation mpls|pw-classpw-class-name}

Example:

Router(config-vfi)# neighbor 10.0.0.1 100 pw-class mpls

Sets up an emulated VC.

•Specify the IP address and the VC ID of the peer router. Also specify the pseudowire class to use for the emulated VC.

Note Only two neighbor commands are allowed for each l2 vfi point-to-point command.

Displaying Information About the L2VPN Multisegment Pseudowires

Perform the following task to display the status of L2VPN multisegment pseudowires.

SUMMARY STEPS

1. show mpls l2transport binding

2. show mpls l2transport vc detail

DETAILED STEPS

Step 1 show mpls l2transport binding

Use the show mpls l2transport binding command to display information about the pseudowire switching point, as shown in bold in the output. (In the following examples PE1 and PE4 are the T-PE routers.)

Router# show mpls l2transport binding

Destination Address: 10.1.1.1, VC ID: 102

Local Label: 17

Cbit: 1, VC Type: Ethernet, GroupID: 0

MTU: 1500, Interface Desc: n/a

VCCV: CC Type: CW [1], RA [2], TTL [3]

CV Type: LSPV [2]

Remote Label: 16

Cbit: 1, VC Type: Ethernet, GroupID: 0

MTU: 1500, Interface Desc: n/a

VCCV: CC Type: CW [1], RA [2], TTL [3]

CV Type: LSPV [2]

PW Switching Point:

Vcid local IP addr remote IP addr Description

101 10.11.11.11 10.20.20.20 PW Switching Point PE3

100 10.20.20.20 10.11.11.11 PW Switching Point PE2

Step 2 show mpls l2transport vc detail

Use the show mpls l2transport vc detail command to display status of the pseudowire switching point. In the following example, the output (shown in bold) displays the segment that is the source of the fault of the multisegment pseudowire:

•To perform a trace operation from T-PE1 to segment 2 of the multisegment pseudowire, enter the following command. destination-address is S-PE1 and vc-id is the VC between T-PE1 and S-PE1.

trace mpls pseudowiredestination-address vc-idsegment 2

This example performs a trace from T-PE1 to S-PE2.

•To perform a trace operation on a range of segments, enter the following command. This example performs a trace from S-PE2 to T-PE2. destination-address is S-PE1 and vc-idis the VC between T-PE1 and S-PE1.

trace mpls pseudowiredestination-address vc-idsegment 2 4

The following commands perform trace operations on S-PE router 10.10.10.9, first on segment 1, then on segment 2.

You can use ping mpls and trace mpls commands to verify connectivity in configurations using the L2VPN VPLS Inter-AS Option B feature. For end-to-end ping and trace operations, you enter the destination address of the T-PE router at the other end of the pseudowire.

Restrictions

Some ping mpls and trace mpls keywords that are available with IPv4 LDP or traffic engineering (TE) are not available with pseudowire.

The following keywords are not available with the ping mplspseudowirecommand:

•dsmap

•flags

•force-explicit-null

•output

•revision

•ttl

The following keywords are not available with the trace mplspseudowirecommand:

•To perform a trace operation from T-PE1 to T-PE2, enter the following command. destination-address is T-PE2 and vc-id is the VC between T-PE1 and S-PE1.

trace mpls pseudowiredestination-address vc-idsegment2

This example performs a trace from T-PE1 to T-PE2.

•To perform a trace operation on a range of segments, enter the following command. This example performs a trace from S-PE2 to T-PE2. destination-address is S-PE1 and vc-idis the VC between T-PE1 and S-PE1.

trace mpls pseudowiredestination-address vc-idsegment 2 4

Configuration Examples for L2VPN Multisegment Pseudowires

This section contains a configuration example for a network similar to the one shown in Figure 2.

Technical Assistance

Description

Link

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Feature Information for L2VPN Multisegment Pseudowires

Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Note Table 2 lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Table 2 Feature Information for L2VPN Multisegment Pseudowires

Feature Name

Releases

Feature Information

L2VPN Multisegment Pseudowires

12.2(33)SRE

This feature enables you to configure two or more Layer 2 pseudowire segments that function as a single pseudowire. The feature spans multiple cores or autonomous systems of the same or different carrier networks.

MPLS OAM Support for Multisegment Pseudowires

12.2(33)SRE

This feature enables you to use the pingmpls and trace mpls commands to verify that all the segments of the MPLS multisegment pseudowire are operating.

MPLS OAM Support for L2VPN VPLS Inter-AS Option B

15.1(1)S

This feature is an enhancement to the MPLS OAM Support for Multisegment Pseudowires feature. This feature allows you to use the pingmpls and trace mpls commands to verify the pseudowire used in a L2VPN VPLS Inter-AS Option B configuration.

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Any Internet Protocol (IP) addresses used in this document are not intended to be actual addresses. Any examples, command display output, and figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses in illustrative content is unintentional and coincidental.